In 2000, Dr. Martin and her coworkers at USDA isolated a purple-pigmented bacteria (PRAA4-1) from a forest soil in Maryland (Martin et al., 2007a). It is a facultatively aerobic, motile, Gram-negative betaproteobacterium with polar flagella. Colonies formed at 2-3 days on an L-agar plate at 25° C. are initially cream colored, gradually turning light to dark violet during the following 24 hours. Colonies of PRAA4-1 grow well on peptone based media with an optimum at 25° C., pH 6.5-8.0, and with 0-1.5% (w/v) NaCl (Martin et al., 2007a). This motile, Gram-negative, bacteria was identified as a new species of Chromobacteria, Chromobacterium substsugae sp. nov (Martin et al., 2007c). and or alternatively as Chromobacterium substsugae NRRL B-30655.
The effect of Chromobacterium substsugae NRRL B-30655 on insects does vary. It has been found to be toxic to Colorado Potato Beetle larvae but not to adults when these insects were fed a diet including Chromobacterium substsugae NRRL B-30655 (Martin, 2007b, 2007c). It was found to be toxic to adult southern green stink bugs but appeared to have a faster effect on males (Martin 2007c). For diamondback moth instar larvae fed a diet including Chromobacterium substsugae NRRL B-30655, the mortality was 90% in 7 days. None of the gypsy moth larvae died following treatment with NRRL B-30655, but the larvae which consumed NRRL B-30655 in their diet were 40% lighter than the controls. For mosquito larvae, there was no mortality at 48 hrs. although the larvae in the B. thuringiensis control were dead in 16 hrs.
With respect to Southern and Western Corn Rootworms, about 80% of both Southern and Western Corn Rootworm adults died when fed Chromobacterium substsugae NRRL B-30655 in a bait formulation; in other assays 100% mortality was reached after 120 hr. (Martin, 2007c). However, mortality in southern corn rootworm larvae was only found to be 40% when fed whole cultures. There was though a difference in the weight in larvae fed NRRL B-306555 as compared to the controls (Martin, 2007c).
US patent application publication no. US20120100236 also discloses compounds obtainable or derived from Chromobacterium species, more particularly, Chromobacterium substugae. In particular, PCT appln. no. PCT/US2012/061503 discloses the use of Chromobacterium species as an acaricide and insecticide, particularly against infestation of one or more pests belonging to the Acarina, Scarabeidae, Drosophilidae, Triozidae, Aphidae, Muscidae, Anthomyiidae or Tenebrionidae families.